Skip to content

Add configurable default chroma subsampling mode for JPEG encoder #819

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Nov 19, 2025
Merged

Add configurable default chroma subsampling mode for JPEG encoder #819

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
69bd642
Add configurable default chroma subsampling mode for JPEG encoder
DT-art1 Nov 8, 2025
2891a5f
Merge branch 'master' into full-chroma-resolution
me-no-dev Nov 19, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 20 additions & 0 deletions conversions/include/img_converters.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,26 @@ bool fmt2rgb888(const uint8_t *src_buf, size_t src_len, pixformat_t format, uint
#define JPG_SCALE_MAX JPEG_IMAGE_SCALE_1_8
bool jpg2rgb565(const uint8_t *src, size_t src_len, uint8_t * out, esp_jpeg_image_scale_t scale);

/**
* @brief Chroma subsampling modes for JPEG encoding.
*
* CHROMA_444: full chroma resolution (4:4:4)
* CHROMA_422: horizontal chroma subsampling (4:2:2)
* CHROMA_420: horizontal and vertical subsampling (4:2:0)
*/
typedef enum {
CHROMA_444 = 1,
CHROMA_422 = 2,
CHROMA_420 = 3
} chroma_t;

/**
* @brief Set default chroma subsampling mode for JPEG encoding.
*
* @param chroma Chroma subsampling mode (CHROMA_444, CHROMA_422, CHROMA_420)
*/
void jpgSetChroma(chroma_t chroma);

/**
* @brief Configure RGB565 input byte order for JPEG encoding.
*
Expand Down
9 changes: 8 additions & 1 deletion conversions/to_jpg.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,8 @@
static const char* TAG = "to_jpg";
#endif


static jpge::subsampling_t default_subsampling = jpge::H2V2;
static bool rgb565_big_endian = true;

static void *_malloc(size_t size)
Expand Down Expand Up @@ -99,7 +101,7 @@ static IRAM_ATTR void convert_line_format(uint8_t * src, pixformat_t format, uin
bool convert_image(uint8_t *src, uint16_t width, uint16_t height, pixformat_t format, uint8_t quality, jpge::output_stream *dst_stream)
{
int num_channels = 3;
jpge::subsampling_t subsampling = jpge::H2V2;
jpge::subsampling_t subsampling = default_subsampling;

if(format == PIXFORMAT_GRAYSCALE) {
num_channels = 1;
Expand Down Expand Up @@ -242,6 +244,11 @@ bool frame2jpg(camera_fb_t * fb, uint8_t quality, uint8_t ** out, size_t * out_l
return fmt2jpg(fb->buf, fb->len, fb->width, fb->height, fb->format, quality, out, out_len);
}

void jpgSetChroma(chroma_t chroma)
{
default_subsampling = static_cast<jpge::subsampling_t>(chroma);
}

void jpgSetRgb565BE(bool enable)
{
rgb565_big_endian = enable;
Expand Down